Articles from June 2015

You will be asked to wear comfortable clothes without metal buttons or zippers, as metal objects affect the quality of the pictures. In some cases you may be asked to exchange your clothing for a comfortable hospital gown.

Remove any jewellery, make-up, prosthesis or credit cards.

You should inform your doctor or technologist if you have a pacemaker, a metal plate, pin or other metallic implant, an artificial heart valve, aneurysm clips, and whether you have ever been wounded during military service or have ever been a metal worker. Any metallic items within the body may cause discomfort or injury when placed in the magnetic field.

Also be sure to tell your doctor if you are pregnant.

The examination setup

Some MR examinations require the administration, into a vein, of a contrast agent – a liquid which enhances the images of your organs and/or blood vessels. After the scan, the contrast agent will be removed from your body by the kidneys.

You will then be positioned by the specialist on the MR table and the coil used to acquire the images will be placed on your chest.

The MR table on which you have been positioned will gently slide into the MR gantry, where it will stay for the duration of the exam. The technologist will leave the room, but stay in constant contact with you via intercom. Relax, and lie as still as possible. There will also be a buzzer next to you, so that you can contact the staff in case you feel uncomfortable.

The scans themselves vary according to the individual examination. Each scan can last up to 3 minutes and the complete exam can take from fifteen to sixty minutes. During this time several dozen images may be taken.

During the exam you will hear an audible knocking sound at certain intervals. This means images are being taken and you should stay very still. The technologist will provide you with special earphones in advance to reduce the noise and increase your comfort.

On completion of the scan you may re-dress and wait while the MR images are reviewed, either on film or monitor by the cardiologist.

How to prepare yourself?

A checklist will be filled in by the technician prior to the scan.

The need for accuracy is vital, as there may be articles in your body that will disqualify you from an MRI scan, for example, implants from previous surgery or slivers of metal, a pacemaker etc. Following the questionnaire, you may sit with the MRI technician to discuss the whole procedure and double-check the pre-scan form.

Having an MRI examination requires very little preparation. It is advisable to go to the bathroom just before your examination, so that you won’t feel the need to go during the examination.

You can normally continue taking any medicine that you have previously been prescribed. Furthermore, if you wish, you can bring a family member or friend. However, they too must make sure that they are carrying no metal objects.

The underlining point as regards preparation for an MRI scan is not to worry. It only takes a short time, is painless and it’s an excellent diagnostic technique.

When performing cardiac MR, particular precautions have to be made due to the use of a very powerful magnetic field. Implanted ferromagnetic objects can pose a serious safety problem. In general, implants are becoming increasingly MR safe and an individual evaluation is carried out for each case.

In general, the following implants are considered (relative) contraindications to cardiac MR:

– Cerebral aneurysm clips

– Intraocular metallic shards

– Cochlear implants

– Automatic cardioverter defibrillators

– Nerve stimulation units

– Most other electronic implants

– Swan-Ganz catheters

– Temporary pacing wires

Patients with implanted cardiac pacemakers have been scanned on rare occasions, but pacemakers are generally considered a contraindication.